The present invention relates to an engaging member, a lens driving mechanism, an imaging apparatus, and a manufacturing method of an engaging member.
In driving devices which reciprocate a shaft member in a axial direction by expansion and contraction of a piezoelectric element so as to slidably move an engaging member which engages with the shaft member by frictional force as disclosed in US2007/035858A1 (counterpart application of JP2007-49878A), it is necessary to keep the engagement state between the shaft member and the engaging member constant in order to stabilize drive performance. In the case of downsizing the driving device in particular, the engagement length of the shaft member and the engaging member is shortened, which tends to cause deteriorated drive performance by the influence of wear of the engagement face and the like.
One of the solutions for this problem is to form a lens mounting rim (holding frame) with metal, though this increases the mass of the lens mounting rim, thereby causing decreased driving force and impact resistance.
In the frictional engagement type driving device for driving a lens by friction engagement method disclosed in US2007/035858A1, a contact surface of an engaging member which comes into contact with a shaft member comprises a member made of metal in order to stabilize the friction engagement force.
As shown in US2007/035858A1, when the contact surface is constituted from a member made by bending a metal plate, a margin of error in bending angle of the metal plate becomes large. Consequently, when the metal plate is bonded with adhesives, the metal plate may lose touch with the engaging member, and when the metal plate is inserted in a mold for molding of the engaging member, the metal plate may lose touch with the mold, which makes it difficult to secure the precision of the contact surface.
In the case of constituting a small-size lens driving mechanism in particular, the displacement in fixing the metal plate and the bending error of the metal plate deflect the optical axis of a lens to a large degree, which causes deteriorated optical performance.
In insertion-molding of the bearing surface of a bearing which holds the shaft by a V-shaped groove, inclination and deflection of the bearing surface can also pose a problem in a similar manner.